Jujube is known in China as zao; it has a history of use there that can be traced back continuously to the Han Dynasty, about 2,000 years ago. The usual English term for the fruit is “Chinese date” and that is because it shares a similar size, stone, and sweetness with the date that we know of from the Date Palm, but it is entirely unrelated botanically. The Chinese fruit is commonly called “jujube” and the botanical name reflects this: Zizyphus jujuba. The plant belongs to the Rhamnaceae, the Buckthorn Family, so-named because of the prevalence of thorny species (rhamnos is the Latin for a thorny bush).

There are two types of the fruit commonly found on the Chinese market: red and black. The red one is called hongzao (hong= red); this one is used for food, and it is collected in vast quantities. The dark brown or black one is heizao (hei= black), more often called dazao (da=large), since this one is somewhat larger. These are not different species but different types, just as one can find, for example, a variety of small red apples and another of large green apples. The black date is steamed, dried, and then smoked; the last part of the processing gives it the characteristic smoky fragrance and flavor.

The fruit is incorporated into the medical tradition in two ways. As a nourishing food, it is thought to tonify qi and strengthen those who are weak and it is especially given to children who would not tolerate a bitter or acrid herb formula, but can consume these fruits. It is used in medicinal formulas to moderate the taste and effect of potent herbs.

In the book The Food of China (1), this description of the fruits is given:

…the main fruit of China’s core area is the jujube or Chinese date. A thorny bush or small tree of the dry parts of North China, this buckthorn takes over railroad embankments, city yards, factory dumps, loess cliff breaks—anywhere too poor and dry for anything else to grow. A favorite yard tree, it bears fruits that look and taste so much like dates that the Western term “Chinese dates” is matched by the Chinese term “foreign jujube” for the true date, known in China as an import since the early Middle Ages. Jujubes are brown or black. Believed to be so powerfully strengthening and health giving, these fruits are fed to infants and used as nutritional aids. Red ones are believed particularly good for the blood [because of their color], black ones for the body in general. A delightful paste of walnuts and jujubes is often eaten for health—the brain-shaped walnut kernels strengthen the brain.

The Indian Materia Medica (2) says of it: “Fruits of the cultivated varieties resemble the crab-apple in flavor and appearance and the pulp is mealy and sweet; they are more palatable and less acid than the wild varieties. When ripe and dried, it is a mild laxative and expectorant. Fruit is often eaten with vegetables; it is also made into a preserve by removing the stone and adding chilies and salt, and the whole fruit is made into a cake.”

The desiccated fruit has been analyzed for nutritional qualities; per 100 grams, it has (3):

Calories: 350; from fat, protein, carbohydrate as follows:

Protein: 7.3 g

Fat: 1.2 g

Carbohydrate: 84 g

Fiber: 4g

Ash: 3.0 g; this is minerals, mainly the following of interest:

Potassium: 1,050 mg

Phosphorus: 168 mg

Calcium: 130 mg

Sodium: 12 mg

Iron: 3.5 mg

Vitamins: about 0.5 g, mainly the following

Vitamin C: 300 mg

Vitamin A: 125 mg

Niacin: 2.8 mg

Riboflavin: 0.2 mg

Thiamine: 0.1 mg

The fruit without water is 84% sugar, which explains its very sweet taste. In a “serving” of 10 grams of desiccated fruit pulp (derived from about one-half ounce of edible dried fruit with the pit removed), the only significant nutrients for a modern diet would be 3.6–3.7 grams of protein and 30 mg of vitamin C.

There may be very little of any “active constituents” in the fruit. Most of the reports of such active ingredients are actually due to errors of interpretation, in that data is mistakenly taken from the analysis of seeds of Zizyphus spinosa (Chinese: suanzaoren) rather than the fruit pulp of Zizyphus jujuba. Zizyphus spinosa, known as spiny zizyphus, wild zizyphus, or sour jujube, yields glycosides that may have significant pharmacological action.

Jujube became a major component of herbal formulas largely from the influence of the Shanghan Lun (ca 200 A.D.). About one third of the Shanghan Lun formulas in decoction form utilize a group of three herbs in support of the main ingredients of the formula: fresh ginger (2–3 liang), seared licorice (2–3 liang), and jujube (4–12 pieces, cut or shredded). The unit of liang at this time in China’s history was around 15 grams; 12 pieces of the jujube fruit (dazao) would be about 1 liang. According to the traditional view, jujube and licorice aid in harmonizing the formula; jujube and ginger regulate the spleen and stomach and harmonize the ying and wei qi. Jujube, a moistening agent (this is mainly because of its sugar content), may cause some abdominal distension, which is prevented by ginger. Ginger, which is stimulating and drying, is toned down by jujube. From the modern view, ginger and licorice would be the main active components of the trio, while jujube would add to the sweetness and, presumably, reduce the sharp spiciness of ginger, at least by taste.

The sweet taste of jujube (and licorice) was thought to counteract toxicity of potent herbs. Jujube is described in the Annotation of Shen Nong’s Herbal: “The herb, being sweet in taste, removes poison of any substance, and is used to harmonize drugs in a prescription (4).” The book Chinese-English Manual of Commonly Used Herbs in Traditional Chinese Medicine (5) lists this action of jujube: “to moderate the potency of drugs: for counteracting the toxicity or side effects of potent drugs, such as genkwa, euphorbia, lepidium, etc.” The use of jujube to counter side-effects of genkwa, euphorbia, and lepidium was evident in the Shanghan Lun formulas. In Commonly Used Chinese Herb Formulas with Illustrations (6), the traditional formula Tingli Dazao Xiefei Tang (Lepidium and Jujube Combination) is listed, and this is mentioned: “To prevent its violent action from harming the lungs, lepidium is subordinated to jujube, which soothes the stomach and harmonizes the action of lepidium so that normal respiration is not harmed.” Genkwa and euphorbia appear together in a single prescription of the Shanghan Lun called Shizao Tang, literally, Ten Jujubes Decoction. According to Formulas and Strategies (7), “The name of this formula is a tribute to the importance of the ten jujubes which are taken to moderate the harsh, downward-draining action of the other herbs, and thereby protect the stomach qi.” The hot, spicy herb evodia is a key ingredient of Wuzhuyu Tang (Evodia Combination); according to Formulas and Strategies: “The envoy, sweet jujube, moderates the acrid, drying properties of the chief and deputy ingredients [evodia and ginger].

What is it about jujube that might have these functions? Based on our modern knowledge, there is probably no actual effect on toxicity of herbs, but only the action of making the decoction seem less drastic in taste, basically by adding sugar. Similarly, the “harmonizing effect” may actually refer to moderating the taste in decoctions, so that they could be better tolerated, rather than suggesting some other integration of the herbal actions. It is possible that the powerful taste of the strong decoctions—when taken without jujube— overpowered some individuals, making them react promptly—not just to any toxicity (which might be there because of the ingredients used) but also because of the nauseating flavor.

Proper Use of Jujube Today

Jujube is included in some traditional style formulas that are made in pill form, but it is probably not an essential ingredient in those cases: it is present in very small quantities and not a factor in the taste of the formula (since it is swallowed without tasting it). However, for those prescribing decoctions, or dried decoctions (granules) taken in tea form, jujube may still serve the same purpose as in ancient times: for affecting the taste. Most of the toxic herbs are no longer used, so that there is not necessary to worry about counteracting their toxicity, but several herbs with very strong taste are still present, such as coptis, phellodendron, and evodia. The amount of jujube used must be adequate to the task: about 10 grams of the fruit or 2 grams of the granules for a one-day dose.

The ancient claims about its extraordinary nutritive qualities may reflect two aspects of jujube: first, persons who were especially weak and unable to eat ordinarily might find the mild and sweet taste of jujube acceptable and at least get some calories (e.g., about 40, still very little) and a small amount of protein, especially valuable if jujube was added to a nutritional dish to make it more palatable; second, persons who did not have much fruit in their diet might have had a low vitamin C level, which could be corrected with a relatively small quantity of jujube fruit or its extract.

There is some tendency to think of herbs listed as qi tonics in the Materia Medica to be rather potent in their effect on qi. However, this is not necessarily the case. If jujube was mainly used to ameliorate the taste of decoctions and to lower the toxicity of potent herbs, it would be relied upon heavily, but not necessarily because it would be a potent qi tonic. Its inclusion in that section of the Materia Medica comes about mainly because of its sweet taste (and lack of other dominant tastes that might shift it to another category).

We may examine one of the more famous formulas with jujube, the combination of licorice, wheat (floating wheat grains), and jujube (Gan Mai Dazao Tang), for treatment of emotional distress (8):

Wheat (fuxiaomai) 15 g, Jujube (dazao) 14 g, Licorice (gancao) 9 g

The main ingredient is the wheat, but we would be unlikely today to consider this food to be a useful sedative. In the same manner, considering the relatively innocuous nature of jujube, it would not be considered a strong sedative (but the seed of the “spiny zizyphus” would).

Unlike some of the other mild herbs of Chinese medicine, jujube would not become more potent by using a larger dose. At a certain point, the sweetness simply becomes overwhelming, but there is not a large amount of another active component that comes along with it. Therefore, its usual dosage, which would correspond to about 6–15 grams of dried fruit, is adequate. A 15 gram portion would provide the equivalent of about 3 teaspoons of table sugar.

REFERENCES

Anderson EN, The Food of China, 1988 Yale University Press, New Haven, CT.